“Autistic brain as the extreme Homo sapiens brain” hypothesis by me, an autistic biology undergrad
(oh boy will this get long and controversial)
To help you understand this hypothesis, first let me break down some evolutionary concepts. Let’s talk about speciation.
New species appears when two things happen: there is a new trait that gives a population better chances of passing on their genes through procreation in a certain environment (apomorphy: a new, derived trait), and there is reproductive isolation from individuals without that trait. New traits appear through random mutations and most of them are harmful. Useful traits get more and more common with every generation until a population separates and can no longer create fertile offspring with those most closely related to them. Wham, speciation.
This is hard to understand if you aren’t into biology so example. There’s a fish which has more muscle in its fins than all other fishes. That trait is new, it’s extreme and rare. However it allows the fish to move better in shallow water, where it has less competition and more food. It produces a lot of offspring, some of which has the same trait. They continue to live in shallow water and they meet other fish that also live in shallow water. Repeat that many many times and you get a new species of Sarcopterigii (muscle fins! technically that’s us). Apomorohy: more muscle in fins; new environment: shallow water; reproductive isolation: geographical.
Now back to humans. Apomorphies of the genus Homo were things like bipedal locomotion, use of tools, language, and so on, and our new territory was the savanna (as opposed to forests). However we still aren’t a sure what defines our species, Homo sapiens, and where to draw the line between hominids and us. My anthropology professor always laughs when talking about Homo species like habilis or erectus because he doesn’t know whether he should call them “males and females” or “men and women”. We just don’t know what is our defining trait(s).
But we do know that there was something about sapiens that allowed us to outlive all other Homo species, including Neanderthals and Denisovans, and it is obvious that we have a difference. Well I am here to present a thrilling new hypothesis: we will realize what that trait is if we study autistic people, because the autistic brain is the extreme Homo sapiens brain. Just like the fins of fish continued to develop to help it navigate land, human brain continued to develop to adapt to our lifestyle, and that adaptation is autism.
Looking at some common autism traits we notice that a lot of them are neurotypical behaviors taken to extreme. Stimming is extreme fidgeting, special interests are extreme hobbies/interests, routines are extreme schedules/planning habits, sensory processing disorder is extreme sensory perception. Hence the intense world hypothesis.
Looking further, we notice that there are other characteristically human traits that autism takes to extreme: like noticing patterns, memory and imagination. Even further, if we look at developing baby brains, we see that if a child’s prefrontal cortex is growing faster and is bigger than typical, that child is more likely to be later diagnosed as autistic. And prefrontal cortex is the most characteristically human part of our brain!
So what I see is that a lot of autistic traits are Homo sapiens traits taken to the next level, and it might come from increased prefrontal cortex growth as well as more local connections between neurons. So arguably a lot of things that were Homo sapiens apomorphies just went further to better suit our new society with all the tool making, hunting, gathering, agriculture, art, science and religion.
Now I hear you saying “but Mattie, humans are very social and autism is a social disability!”. Well yeah, you’re right: social interaction problems are major autism criteria. However I’d like to talk about why that is the case. Autistics struggle with social protocol, which is supposedly a set of unspoken rules of existing in human society that relies on ability to read certain cues like facial expressions, body language, tone of voice and so on. And yes the majority of autistics suck at that.
But you know what? So do allistics! I know it sounds counterintuitive but social protocol is shit. It is constantly changing, imprecise, highly dependent on time and culture and impossible to define. It’s just sloppy. Allistics think they are masters of reading social cues but in reality they are making a ton of guesses. Research shows that cognitive empathy (subconscious guesses based on all that body language and stuff) is worse than conscious analyses, meaning that I, an autistic person who has to use conscious analyses to understand others, is technically better at it than an allistic person who uses cognitive empathy.
Allistics get away with this because they are the majority. When everyone’s bad at something together, there’s no way of telling you’re bad at it. They are flexible and go with the flow and they don’t see how illogical and sloppy social protocol is. But still, miscommunication is the most common comedy trope and there’s always so much misunderstanding in society, which means it is not perfect.
Autistics however seek structure, predictability and order. Sloppy and illogical isn’t good enough for us. Our brains just can’t find patterns in that mess of social cues. So if we were the majority, we would not get away with hints and subsequent miscommunication. I think we would develop a much more structured and well-defined social protocol which would leave much less room for misinterpretation and ensure better communication. Maybe we would have a system of gestures and hand signs to communicate different things, maybe we would use technology, maybe our language would change to accommodate it. Either way, if we were the majority, there would be no social disability.
Now you may ask, well if autistics are extreme humans, why haven’t we replaced allistics as a phenotype more suited for life in our environment? Well, civilization happened and natural selection went to hell. Now we don’t change to fit the environment, we change the environment to fit us. And because the autistic neurotype was still that extreme, rare, “weird fish with muscly fins” population, we got screwed over. Allistics - the majority - built a world which was great for them and incredibly bad for us. It became especially prominent from the rise of industrial revolution, and even more prominent in the last hundred years, which is when it was described for the first time and is now diagnosed in like 1-2% of the population.
I don’t think autism has a chance to become more common now, because due to ableism and other reasons we are less likely to procreate. Autistics aren’t gonna create a new species either because we have no reproductive isolation now. The only thing we can do is to change the environment through education and accommodation to make it better for us, and maybe autism will stop being a disability some day.
However I think it is important to study autism, and not with a purpose of preventing us from being born, but because it may reveal the truth about the nature of humanity and show us what might have happened to our species if it wasn’t for civilization. In my opinion it is just fascinating and it might finally prove why we need accommodation for autism and how to do it the best. Until then, these are just random thoughts of a nerd obsessed with biology.
If you have any thoughts about this, please let me know.